1. Field of the Invention
This invention relates to athletic shoes, and in particular to shoes used for running where the user's body weight exceeds one hundred forty pounds.
2. Description of the Prior Art
In recent years, burgeoning interest in physical fitness and health has resulted in vast numbers of people pursuing running as a means of conditioning their bodies. Unfortunately, injuries to the joints, muscles, ligaments and tendons of the runner's lower extremeties has increased due in no small measure to ill-fitting and poorly designed running shoes. During contact of the running shoe with the running surface, a force of three to eight times body weight impacts on the runner's foot. The impact of the foot is absorbed by the running shoe or transmitted directly to the leg. The results of this impact on the foot and leg due to improperly designed shoes can be shin splints, muscle soreness, hamstring strains, stress fractures and sore knee joints.
Many devices have been proposed and patented over the years to improve the design and function of running shoes. U.S. Pat. No. 4,402,146 to Parracho et al discloses a running shoe sole with heel tabs to increase lateral stability and reduce ankle fatigue. U.S. Pat. No. 4,430,810 to Bente discloses an outer sole for sports shoes having adjustable sole fexibility in the heel region adaptable to the individual requirements of the runner and track. U.S. Pat. No. 4,364,188 to Turner et al discloses a running shoe with a rear stabilization means to decrease the tendency to overpronation.
Other patents of interest relating to athletic shoes include U.S. Pat. No. 4,235,026; U.S. Pat. No. 4,378,643; U.S. Pat. No. 4,255,877; U.S. Pat. No. 4,245,406; U.S. Pat. No. 4,128,950 and U.S. Pat. No. 4,307,521. Although these shoes ameliorate to some extent the effects of impact shock to the foot, they do not completely resolve the problems.